I'll answer the second question, first. Read through most of this blog and also check out this blurb.
Now to the first question. You pay for title insurance once. That is, once for each policy.
Your owner policy stays in place and protects you as long as you have an interest to protect.
Loan policies, on the other hand, expire when the underlying mortgage is paid in full. If you get another mortgage, you'll pay for another loan policy. That's why regulators encourage or require discounts in certain refinance transactions.